Análisis estructural 3D de los invernaderos multitunel del sudeste de España. Elementos verticales

Este trabajo analiza la capacidad estructural de los elementos verticales que componen el pórtico resistente más limitativo de la variante de invernadero multitúnel más utilizada en el sudeste de España. Se estudia la influencia de la longitud y anchura del invernadero en la distribución de tensiones que se produce en dichos elementos. Se ha realizado un modelo tridimensional de elementos finitos con el programa ROBOT MILLENNIUM en su versión 20.1 en el que se ha representado la estructura de barras que conforma el invernadero. Se han analizado los resultados de tensiones normales máximas de 16 estructuras con geometría de túnel similar, pero de diferente anchura y longitud, de tal forma que la superficie en planta oscila entre los 600 m 2 y los 38.400 m 2 . El cálculo de las acciones existentes sobre los invernaderos se ha realizado según la norma UNE-EN 13031-1. Los resultados numéricos obtenidos han sido estudiados para determinar la influencia de las dimensiones del invernadero en la distribución de tensiones. Aunque se observan significativas reducciones en las tensiones con la adición de túneles, no se puede generalizar la influencia del aumento de las dimensiones del invernadero en los cambios tensionales del mismo. Los resultados obtenidos se consideran de gran utilidad para la optimización de las estructuras de los invernaderos multitúnel así como para garantizar la seguridad mecánica de las mismas

Análisis estructural 3D de los invernaderos multitunel del sudeste de España. Elementos horizontales

Este trabajo analiza la capacidad estructural de los Este trabajo analiza la capacidad estructural de los elementos horizontales que componen el pórtico resistente más limitativo de la variante de invernadero multitúnel más utilizada en el sudeste de España. Se analiza la influencia de la anchura y longitud del invernadero en la distribución de tensiones que se producen en dichos elementos. Se ha realizado un modelo tridimensional de elementos finitos con el programa ROBOT MILLENNIUM en su versión 20.1 en el que se ha representado la estructura de barras que conforma el invernadero. Se han analizado los resultados de tensiones normales máximas de 16 estructuras con geometría de túnel similar, pero de diferente anchura y longitud, de tal forma que la superficie en planta oscila entre los 600 m 2 y los 38.400 m 2 .El cálculo de las acciones existentes sobre los invernaderos se ha realizado según la norma UNE-EN 13031-1. El aumento de las dimensiones del invernadero conlleva importantes variaciones en las tensiones máximas registradas por canalones. Sin embargo, en arcos y tirantes de cercha, las tensiones permanecen constantes. Los resultados obtenidos se consideran de gran utilidad para la optimización de las estructuras de los invernaderos multitúnel así como para garantizar la seguridad mecánica de las mismas.

c&d-learning implementation architecture: Adapting e-learning to developing countries

From the educational point of view, the most widespread method in developing countries is on-site education. Technical and economic resources cannot support conventional distance learning infrastructures and it is even worse for courses in universities. They usually suffer a lack of qualified faculty staff, especially in technical degrees. The literature suggest that e-learning is a suitable solution for this problem, but its methods are developed attending to educational necessities of the First World and cannot be applied directly to other contexts. The proposed methodology is a variant of traditional e-learning adapted to the needs of developing countries. E-learning for Cooperation and Development (c&d-learning) is oriented to be used for educational institutions without adequate technical or human resources. In this paper we describe the c&d-learning implementation architecture based on three main phases: hardware, communication and software; e.g. computer and technical equipping, internet accessing and e-learning platform adaptation. Proper adaptation of educational contents to c&d-learning is discussed and a real case of application in which the authors are involved is described: the Ngozi University at Burundi.

YUCCA8 and YUCCA9 overexpression reveals a link between auxin signaling and lignification through the induction of ethylene biosynthesis.

Auxin is associated with the regulation of virtually every aspect of plant growth and development. Many previous genetic and biochemical studies revealed that, among the proposed routes for the production of auxin, the so-called indole-3-pyruvic acid (IPA) pathway is the main source for indole-3-acetic acid (IAA) in plants. The IPA pathway involves the action of 2 classes of enzymes, tryptophan-pyruvate aminotransferases (TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1(TAA1)/TRYPTOPHAN AMINOTRANSFERASE RELATED (TAR)) and flavin monooxygenases (YUCCA). Both enzyme classes appear to be encoded by small gene families in Arabidopsis consisting of 5 and 11 members, respectively. We recently showed that it is possible to induce transcript accumulation of 2 YUCCA genes, YUC8 and YUC9, by methyl jasmonate treatment. Both gene products were demonstrated to contribute to auxin biosynthesis in planta.1 Here we report that the overexpression of YUC8 as well as YUC9 led to strong lignification of plant aerial tissues. Furthermore, new evidence indicates that this abnormally strong secondary growth is linked to increased levels of ethylene production.

Valuation of a new entrant in an oligopolistic market, including its option to abandon: A real-life case

The purpose of this paper is to increase current empirical evidence on the relevance of real options for explaining firm investment decisions in oligopolistic markets. We study an actual investment case in the Spanish mobile telephony industry, the entrant in the market of a new operator, Yoigo. We analyze the option to abandon in order to show the relevance of the possibility of selling the company in an oligopolistic market where competitors are not allowed free entrance. The NPV (net present value) of the new entrant is calculated as a starting point. Then, based on the general approach proposed by Copeland and Antikarov (2001), a binomial tree is used to model managerial flexibility in discrete time periods, and value the option to abandon. The strike price of the option is calculated based on incremental EBITDA margins due to selling customers or merging with a competitor.

Cloud Computing Service for Managing Large Medical Image Data-Sets Using Balanced Collaborative Agents

Managing large medical image collections is an increasingly demanding important issue in many hospitals and other medical settings. A huge amount of this information is daily generated, which requires robust and agile systems. In this paper we present a distributed multi-agent system capable of managing very large medical image datasets. In this approach, agents extract low-level information from images and store them in a data structure implemented in a relational database. The data structure can also store semantic information related to images and particular regions. A distinctive aspect of our work is that a single image can be divided so that the resultant sub-images can be stored and managed separately by different agents to improve performance in data accessing and processing. The system also offers the possibility of applying some region-based operations and filters on images, facilitating image classification. These operations can be performed directly on data structures in the database.

Low-Profile Dual Circularly Polarized Antenna Array for Satellite Communications in the X Band

A planar antenna is introduced that works as a portable system for X-band satellite communications. This antenna is low-profile and modular with dimensions of 40 × 40 × 2.5 × cm. It is composed of a square array of 144 printed circuit elements that cover a wide bandwidth (14.7%) for transmission and reception along with dual and interchangeable circular polarization. A radiation efficiency above 50% is achieved by a low-loss stripline feeding network. This printed antenna has a 3 dB beamwidth of 5°, a maximum gain of 26 dBi and an axial ratio under 1.9 dB over the entire frequency band. The complete design of the antenna is shown, and the measurements are compared with simulations to reveal very good agreement.

Reconstrucción ideal de un artesonado de la iglesia de Sta. Mª de la Cuesta de Durón a partir de los elementos encontrados durante su restauración

El lamentable estado del templo hizo que Luis de Villanueva y Susana Mora redactaran un Proyecto de Restauración, cuya primera fase era la Restauración de cubiertas. Éstas se desmontaron cuidadosamente, apareciendo en la nave sur una viga cambiada de posición de labra supuestamente mudéjar, lo que hizo exagerar las precauciones. Pudimos así observar otra ménsula de madera labrada que servía de apoyo a elementos pétreos de la cabecera. En la nave lateral norte se encontraron durmientes, varios tirantes, y rebajes equidistantes, que podrían corresponder a estribos. En la nave central, formando parte de las quijeras, estaban integrados elementos con sencillas decoraciones azuladas, que podrían corresponder a restos de los citados estribos de la nave lateral. Las hipótesis se comprobaron, y con el apoyo de textos especializados, se formuló una propuesta de techumbre que podría acercarnos a las construcciones de esta zona del Señorío de Mendoza entre los siglos XV y XVI.

Qualitative Monitoring of Video Quality of Experience

Real-time monitoring of multimedia Quality of Experience is a critical task for the providers of multimedia delivery services: from television broadcasters to IP content delivery networks or IPTV. For such scenarios, meaningful metrics are required which can generate useful information to the service providers that overcome the limitations of pure Quality of Service monitoring probes. However, most of objective multimedia quality estimators, aimed at modeling the Mean Opinion Score, are difficult to apply to massive quality monitoring. Thus we propose a lightweight and scalable monitoring architecture called Qualitative Experience Monitoring (QuEM), based on detecting identifiable impairment events such as the ones reported by the customers of those services. We also carried out a subjective assessment test to validate the approach and calibrate the metrics. Preliminary results of this test set support our approach.

The ballast pick-up problem. A theoretical approach and two experimental campaigns

The aim of this contribution is to present a theoretical approach and two experimental campaigns (on wind tunnel and on the track) concerning the research work about the ballast train-induced-wind erosion (BTIWE) phenomenon. When a high speed train overpasses the critical speed, it produces a wind speed close to the track large enough to start the motion of the ballast elements, eventually leading to the rolling of the stones (Kwon and Park, 2006) and, if these stones get enough energy, they can jump and then initiate a saltation-like chain reaction, as found in the saltation processes of soil eolian erosion (Bagnold, 1941). The expelled stones can reach a height which is larger than the lowest parts of the train, striking them (and the track surroundings) producing considerable damage that should be avoided. There is not much published work about this phenomenon, in spite of the great interest that exists due to its relevant applications in increasing the maximum operative train speed. Particularly, the initiation of flight of ballast due to the pass of a high speed train has been studied by Kwon and Park (2006) by performing field and wind tunnel experiments.

X-parameters based analytical design of non-linear microwave circuits Application to oscillator design

Resumen El diseño clásico de circuitos de microondas se basa fundamentalmente en el uso de los parámetros s, debido a su capacidad para caracterizar de forma exitosa el comportamiento de cualquier circuito lineal. La relación existente entre los parámetros s con los sistemas de medida actuales y con las herramientas de simulación lineal han facilitado su éxito y su uso extensivo tanto en el diseño como en la caracterización de circuitos y subsistemas de microondas. Sin embargo, a pesar de la gran aceptación de los parámetros s en la comunidad de microondas, el principal inconveniente de esta formulación reside en su limitación para predecir el comportamiento de sistemas no lineales reales. En la actualidad, uno de los principales retos de los diseñadores de microondas es el desarrollo de un contexto análogo que permita integrar tanto el modelado no lineal, como los sistemas de medidas de gran señal y los entornos de simulación no lineal, con el objetivo de extender las capacidades de los parámetros s a regímenes de operación en gran señal y por tanto, obtener una infraestructura que permita tanto la caracterización como el diseño de circuitos no lineales de forma fiable y eficiente. De acuerdo a esta filosofía, en los últimos años se han desarrollado diferentes propuestas como los parámetros X, de Agilent Technologies, o el modelo de Cardiff que tratan de proporcionar esta plataforma común en el ámbito de gran señal. Dentro de este contexto, uno de los objetivos de la presente Tesis es el análisis de la viabilidad del uso de los parámetros X en el diseño y simulación de osciladores para transceptores de microondas. Otro aspecto relevante en el análisis y diseño de circuitos lineales de microondas es la disposición de métodos analíticos sencillos, basados en los parámetros s del transistor, que permitan la obtención directa y rápida de las impedancias de carga y fuente necesarias para cumplir las especificaciones de diseño requeridas en cuanto a ganancia, potencia de salida, eficiencia o adaptación de entrada y salida, así como la determinación analítica de parámetros de diseño clave como el factor de estabilidad o los contornos de ganancia de potencia. Por lo tanto, el desarrollo de una formulación de diseño analítico, basada en los parámetros X y similar a la existente en pequeña señal, permitiría su uso en aplicaciones no lineales y supone un nuevo reto que se va a afrontar en este trabajo. Por tanto, el principal objetivo de la presente Tesis consistiría en la elaboración de una metodología analítica basada en el uso de los parámetros X para el diseño de circuitos no lineales que jugaría un papel similar al que juegan los parámetros s en el diseño de circuitos lineales de microondas. Dichos métodos de diseño analíticos permitirían una mejora significativa en los actuales procedimientos de diseño disponibles en gran señal, así como una reducción considerable en el tiempo de diseño, lo que permitiría la obtención de técnicas mucho más eficientes. Abstract In linear world, classical microwave circuit design relies on the s-parameters due to its capability to successfully characterize the behavior of any linear circuit. Thus the direct use of s-parameters in measurement systems and in linear simulation analysis tools, has facilitated its extensive use and success in the design and characterization of microwave circuits and subsystems. Nevertheless, despite the great success of s-parameters in the microwave community, the main drawback of this formulation is its limitation in the behavior prediction of real non-linear systems. Nowadays, the challenge of microwave designers is the development of an analogue framework that allows to integrate non-linear modeling, large-signal measurement hardware and non-linear simulation environment in order to extend s-parameters capabilities to non-linear regimen and thus, provide the infrastructure for non-linear design and test in a reliable and efficient way. Recently, different attempts with the aim to provide this common platform have been introduced, as the Cardiff approach and the Agilent X-parameters. Hence, this Thesis aims to demonstrate the X-parameter capability to provide this non-linear design and test framework in CAD-based oscillator context. Furthermore, the classical analysis and design of linear microwave transistorbased circuits is based on the development of simple analytical approaches, involving the transistor s-parameters, that are able to quickly provide an analytical solution for the input/output transistor loading conditions as well as analytically determine fundamental parameters as the stability factor, the power gain contours or the input/ output match. Hence, the development of similar analytical design tools that are able to extend s-parameters capabilities in small-signal design to non-linear ap- v plications means a new challenge that is going to be faced in the present work. Therefore, the development of an analytical design framework, based on loadindependent X-parameters, constitutes the core of this Thesis. These analytical nonlinear design approaches would enable to significantly improve current large-signal design processes as well as dramatically decrease the required design time and thus, obtain more efficient approaches.

Modular Planar Antenna at X-band for satellite communications

An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 [1] and ITU-R S.465-5 [2] for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization

Portable low profile antenna at X-band

An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 and ITU-R S.465-5 for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band with a VSWR of 1.4:1. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization.

Automatic lateral control for unmanned vehicles via genetic algorithms

It is known that the techniques under the topic of Soft Computing have a strong capability of learning and cognition, as well as a good tolerance to uncertainty and imprecision. Due to these properties they can be applied successfully to Intelligent Vehicle Systems; ITS is a broad range of technologies and techniques that hold answers to many transportation problems. The unmannedcontrol of the steering wheel of a vehicle is one of the most important challenges facing researchers in this area. This paper presents a method to adjust automatically a fuzzy controller to manage the steering wheel of a mass-produced vehicle; to reach it, information about the car state while a human driver is handling the car is taken and used to adjust, via iterative geneticalgorithms an appropriated fuzzy controller. To evaluate the obtained controllers, it will be considered the performance obtained in the track following task, as well as the smoothness of the driving carried out.